1. Field of the Invention
The present invention relates to an apparatus for effecting hyperthermia in a narrow body cavity or duct. The invention is especially applicable to the treatment of the endometrium of the uterus. The treatment resides in a combination of the supply of heat to said body cavity or duct and simultaneous application of a controlled pressure on surrounding tissue.
2. Background Art
In the treatment of certain disorders in narrow body cavities or ducts the supply of heat is frequently used, the treatment residing in so called hyperthermia. For use in such treatment several apparatuses have been described including a special catheter employing a balloon attached to the distal end of the catheter. In the treatment of for example menorrhagia the distal end of the catheter including the balloon is inserted into the uterus cavity via vagina and cervix, the balloon being them  then expanded using a pressure medium up to a suitable pressure. The catheter includes heat-releasing means, for example an electric resistance element, to which electric energy is supplied from the exterior via the catheter, the generated energy and the temperature being controlled in different ways (see for example PCT/US89/03916).
In copending application PCT/SE92/00645 there is described an apparatus for carrying out hyperthermia involving the use of a heat-releasing element which is of an inherently self-regulating type. Examples of such elements are elements based on materials of the PTC-type or ferromagnetic materials where the means for the supply of energy are based on magnetic induction. In accordance with said PCT-application the problem of creating sufficient power output while avoiding self-inhibition associated with a heating element of the self-controlling type has been solved by arranging the element in a surrounding elongate housing through which the heat-transmitting medium is forced through and around the element by efficient internal circulation. Such internal circulation around and through the heat-releasing element is generated by providing a reciprocating movement of a small quantity of the pressurized quantity of heat-medium.
For details concerning this background art reference is made to the above-identified patent application PCT/SE92/00645, the full disclosure of which is incorporated herein by reference.
In apparatuses as those described above the balloon catheter is thus connected to sources for the supply of a liquid medium, electric energy and means for the control of the temperature and the supply of energy. In the apparatus according the above-mentioned PCT-application no means for temperature control are necessary but means for the generation of a reciprocating movement of a small quantity of the liquid medium will be required.
In the device according to the above PCT-application the liquid medium transferring heat to the area to be treated is in the form of a sterile liquid enclosed in a catheter, the distal part of which carries a distensible enclosure or balloon intended to be inserted in for example a uterus cavity. Due to this arrangement it is clear that not only the exterior parts of the catheter but also the interior thereof must be capable of cleaning and sterilization after use in view of the fact that leakage can result in infection of the enclosed liquid and thereby also the catheter parts. Even if a catheter is of a disposable type and is disposed of after use the means connected to the catheter, such as the means for generating pressure and internal circulation, will have to be cleaned and sterilized after every use since they have been in contact with the liquid medium. Such cleaning and sterilization is a very complicated and expensive procedure.
The present invention has for an object to provide a system meeting and requirements as to sterility.
Another object of the invention is to provide an apparatus where any risk of contamination from a preceding treatment is excluded.
Yet another object of the invention is to eliminate the risk for contamination and transfer of infection at a low cost for each treatment.
Still another object of the invention is to enable control and adjustment of the optimum average pressure during the course of treatment.
A further object of the invention is to provide a system through which excessive pressures hazardous to the patient can be avoided.
These and other objects will be obtained in accordance with the present invention by an apparatus for effecting hyperthermia in a narrow body cavity or duct, said apparatus being composed of a first disposable part comprising all constructional details subject to contamination, and a permanent non-disposable second part comprising the equipment necessary for operating the apparatus.
Accordingly, the present invention provides an apparatus for carrying out hyperthermia in a narrow body cavity or duct, said apparatus comprising:
a disposable first part comprising an elongate distal section intended to be inserted into said cavity or duct comprising a centrally located, heat-releasing element, which is either surrounded by an elongate housing or is itself constituted by an elongate housing, and a flexible and/or elastic enclosure surrounding said housing in a liquid-tight manner, further including means for supplying energy to the heat-releasing element end an axially operating first inlet at the proximal part of the housing, an outlet from the housing being arranged for the supply of heat-transmitting medium under pressure for expansion of the flexible enclosure to accomodate and to exert a controlled pressure on surrounding walls to said cavity or duct, a second inlet to the housing, and medium-actuating means for said expansion of the flexible enclosure and for internal circulation of said medium through the housing; and
a permanent non-disposable part comprising drive means for said means for said expansion and for internal circulation, and connecting means for unfastenably interconnecting said drive means and said means for expansion and internal circulation.
In a preferred embodiment of the apparatus of the invention said medium-actuating means comprise a first means for the expansion of the flexible enclosure and a second means for the internal circulation of the medium.
It is particularly preferred that said first means for the expansion of the flexible enclosure by introduction of heat-transmitting medium thereto is capable also of bringing the enclosure into a collapsed condition enabling withdrawal of the instrument from the body cavity or duct.
It is preferred that said second means involves the use of a reciprocating element creating a reciprocating motion to a determined quantity of pressurized medium. Said reciprocating element is suitably part of an injection syringe, although it is conceivable to use other types of reciprocating elements, such as a bellows or a deformable non-elastic container, as will be illustrated in the following description of preferred embodiments.
Said first means for the expansion of the flexible enclosure may likewise be constituted by an ordinary injection syringe, but also in this case the syringe can be replaced by other devices capable of performing the same function, which is also illustrated more in detail below.
For the creation of a reciprocating motion to said reciprocating element it is suitable to use a device comprising an eccentric capable of converting a rotary motion to a rectilinear motion.
Said means for expansion and for internal circulation can be either constituted by two different syringes separately operable for expansion on the one hand and for internal circulation on the other hand. As an alternative one and the same syringe can be used for providing both expansion and internal circulation, thus simplifying the construction.
According to still another aspect of the invention the apparatus can be supplemented with a pressure control system residing in a second distensible enclosure, the interior of which is in communication with the interior of said flexible enclosure, whereby any undesired pressure arising in the flexible enclosure will be released through distention of said second enclosure.
In such embodiment it is preferred that the second enclosure has a higher resistance to distention than the flexible enclosure associated with the distal part of the catheter.
In a preferred embodiment of such supplemented apparatus there is arranged a non-elastic container surrounding the second enclosure, and such container is suitably provided with means for controlling the pressure within the container and outside of the second enclosure. In this manner the level of release of an arising excessive pressure can be adjusted.
In the above-identified PCT/SE92/00645 application a number of embodiments relating to the internal circulation system are described. Furthermore, said application describes different types of heat-releasing elements, a preferred type being a heat-release element based on a PTC-material. For details regarding such features reference is made to said PCT-application.